engAznar, M.Manyà, J. J.García, G.Sánchez, J.L.Murillo, M. B.Influence of freeboard temperature, fluidization velocity and particle size on tar production and composition during the air gasification of sewage sludgeART-2008-60984The influence of freeboard temperature, fluidization velocity, and particle size on tar production and composition during the air gasification of dried sewage sludge has been researched using a bench-scale gasifier. Of the operating variables analyzed, the results obtained from a statistical analysis (ANOVA and PCA) indicate that only the freeboard temperature has a significant influence on tar production. The results also show that freeboard temperature is the key factor that influences the tar composition. A high freeboard temperature reduces the amount of tar produced, but the tar compounds obtained are mainly PAH, which could require a more complicated secondary treatment for tar removal. Nevertheless, an increase in the freeboard temperature value implies a substantial increase in both low heating value and cold gas efficiency (6.5% and 10.8%, respectively, when the required freeboard temperature was increased from 873 to 1123 K). Future studies should focus on testing/developing catalytic materials able to degrade (in a secondary treatment) tar with a high content of PAH compounds.2008http://zaguan.unizar.es/record/150414http://zaguan.unizar.es/record/150414oai:zaguan.unizar.es:150414Energy and Fuels 22, 4 (2008), 2840-2850All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/openAccess